Vapor generator with high temperature pendent superheater platens



M y 1953 G. J. SCHOESSOW 2,834,324

VAPOR GENERATOR WITH HIGH TEMPERATURE PENDENT SUPERHEATER PLATENS Filed Feb. 12.- 1953 5 Sheets-Sheet 1 INVENTOR 242 @1921 JScizassson F l G. 1 a

ATTORNEY M y 1958 G. J. SCHOESSOW 2,834,324

VAPOR GENERATOR WITH HIGH TEMPERATURE PENDENT SUPERHEATER PLATENS Flled Feb 12 1953 5 Sheets-Sheet 2 FIG.2O

INVENTOR g/en JSchoessow B 1! M V L E n l 2 Z 2 "m 7 1 E w A m TTO R N EY y 13, 1958 G. J. scHoEssow 2,834,324

VAPOR GENERATOR WITH HIGH TEMPERATURE PENDENT SUPERHEATER PLATENS Fild Feb. 12, 1953 5 Sheets-Sheet 3 FIG.5

INVENTOR g/e22 J 50170855074 ATTORNEY M y 1958 G. J. SCHOESSOW 2,834,324

VAPOR GENERATOR WITH HIGH TEMPERATURE PENDENT SUPERHEATER PLATENS 5 Sheets-Sheet 4 Filed Feb. 12, 1955 WOUUMUWO O 000000 0000000 oooo0ooo 000000 8 00000 toooo 0oo0oOoo OOOc0o OOOOOO (B00000 0O0OOOCD 000000 76 /3OOQOO0DOOOOOO OOOOOCD 000000 ,0 000000 M00000 OO0O0OOO 000000 264 /4/ 00OO0O 3000000 /OOOOOOO 000000 fiOOOOOO 3000000 OO000Q0O 000000 4o /6 92 000000 0000000 0000000 000000 000000 0000000 OOOOOOOO 000000 O00OOOOO0O000 IfZOOOOOOOO 000000 gwo CDOOCPQDOOOJQUWUJQIJWWPCOU F [(514 INVENTOR 6/627 jscfioessou F ,l G. 13 ATTORNEY y 13, 1958 G. J. SCHOESSOW I 2,834,324

VAPOR GENERATOR WITH HIGH TEMPERATURE PENDENT SUPERHEATER PLATENS 5 Sheets-Sheet 5 Filed Feb. 12, 1955 FIG.7 F|G.8

F l G. 15

INVENTOR g/en J5ch0ess0w' m fi/ ATTORNEY United States Patent VAPOR GENERATOR WITH HIGH TEMPERA- TURE PENDENT SUPERHEATER PLATENS Glen J. Schoessow, Barberton, Ohio, assignor to The Babcock & Wilcox- Company, New York, N. Y., a corporation of New Jersey Application February 12, 1953, SerialNo. 336,525

11 Claims. .(Cl. 122-476) employ a superheater operating at high temperature. To attain this result it is necessary to dispose the tubular elements of the superheater in a zone in which the heating gases are of high heat content and high temperature. This is particularly-true when a predetermined high superheat temperature is to be maintained ,over a wide load range including particularly low loads. When slag forming fuels. are burned in the furnace of the unit thepertinent superheater zone has temperatures above the fusion temperature of the non-combustible of the -,fuel at least throughout a part of the load range. Such a location of superheater surfaces therefore involves. the danger of slag or ash deposit, and when the surfaces are of a convection and radiant type the danger of bridging between adjacent tubes is involved.

The gas temperatures in the superheating zone for the high superheats above indicated, also'approach temperatures at which the metal of the superheater tubes would be substantially weakened and the superheater possibly destroyed were it not for the cooling effect of the steam flowing through the tubes.

In practice, the superheater tubes are in spaced distribution acrossthe gas flow and the flow of steam through the tubes is so proportioned with reference to the gas flow over'the tubes that the metal temperature of the tubes will be maintained Within allowable limits. There are, thus, several operative relationships which must be maintained within design limits .if the superheater is to be reliable in effecting optimum steam temperatures over long periods of time. ample, if normal gas temperatures are maintained over For experiods of decreased steam flow, the superheater metal will be weakened by the excessively high temperatures and lack of compensating metal cooling. The design spaced distribution of the tubular elements of the superheater must be maintained to prevent such weakening of the tubes. This is a diflicult problem in high capacity :superheatersnemploying tube lengths of from 20 to 50 .feet and arranged as superheater platens, parts of which are contacted by gases of a temperature of the order of the fusion temperature of the superheater tubes. 'The optimum spacing of the superheater platens and tubes must be maintained by metal elements or projections secured to the tubes externally thereof and therefore subject to increased exposure to the high temperature gases. The provision of such superheater tube spacing projections is therefore limited by the decreased cooling effect of the steam upon them. This cooling effect is additionally :decreased in parts of the superheater tubes in which "the temperature differential between-the gas temperature sand thetemperatureof the steam within the tubes has ice been decreased as a result of the design pressure of the unit and additionally by the heating of the steam in the superheater tubes beforethe pertinent position of the high temperature superheater is reached.

The above indicated problems are further complicated when the superheater tubes are disposed in long pendent platents disposed above a furnace which is being fired with a slag forming fuel. Under these conditions, parts of succeeding superheater platens (transversely of gas flow) subject to the highest gas temperatures must be widely spaced in order to prevent the excessive accumulations of slag formed by the burning fuel, and to prevent the bridging of such accumulations from one platen to the other.

The present invention solves these problems .by providing alternately long and short superheater platens, with additional superheater circuit tubes acting as platen spacer tubes and extending transversely through the platens, with metal projections upon the additional superheater tubes to maintain the platens in their operative positions, and with other superheater tube guide means securing the tubular components of the platens in their operative relationships while permitting small relative movements therebetween due to thermal changes, and with means arranged on the spaced platens to maintain the platen spacer tube in its operative position. The arrangement of these pertinent means and elements is such that small relative movements of the platen spacer tubes and the platens and the platen components may take place within allowable limits, in order that undesirable stresses, due to thermal changes, are prevented.

The various features of novelty which characterize the invention are pointed out with particularity in claims annexed to and forming a part of this specification, but for a better understanding of the invention, its'operative advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter which discloses a preferred embodiment of the invention.

In the drawings:

Fig. 1 is a sectional elevation of a high temperature and high pressure vapor generating and superheating unit, exemplifying the type of fluid heat exchange unit in which the invention is involved;

Fig. 2 is a partial sectional plan on the horizontal plane of the section line 22 of Fig. 1, showing the horizontal spacing of the superheater platens at the upper part of the superheater in which both long and short platens are disposed;

Fig. 3 is a partial sectional plan On the horizontal plane of the line 3-3 of Fig. 1, showing the spacing of the longer platens only;

Pig. 4 is a digrammatic view to clearly indicate the vapor flow through the superheater headers, and through the long and short platens connected to the headers;

Fig. 5 is a diagrammatic view in the nature of .a front elevation of the superheater, particularly emphasizing the vapor circuit tubes or superheater platen spacer tubes which pass through the superheater platens and are so associated therewith as to maintain the operative spacing of the superheater platens; i

Fig. 6 is a view in the nature of a side elevation of the superheater, showing particularlyfurther details ofthe construction and arrangement vapor circuit tubes which act as superheater platen guides, or spacers;

Fig. 7 is a side elevation of the superheater, showing particularly the long superheater platens, and the crossover tubes leading from one long superheater platensto the adjacent similar platen;

.Fig, 8 is an end elevation of a. pair of the short superheater platens with their connected headers and crossover tubes;

Fig. 9 is a fragmentary vertical section on the line 99, Fig. 5, showing, on a greatly enlarged scale, the superheater guide or spacer arrangement of elements including a part of the horizontal superheater guide tube where it passes between the innermost tubes of the long superheater platens, such positions being indicated at the lower parts of Fig. 7;

Fig. 10 is a fragmentary plan of the elements shown in Fig. 9, showing some of the lug attachments welded to the facing and innermost tubes of a loop of a long superheater platen and also showing some of the lug attachments welded to the horizontal part of one of the vapor circuit tubes constituting superheater platen guide or spacer tubes;

Fig. 11 is a fragmentary vertical section similar to Fig. 9, and on the line 11-11 of Fig. 5, but showing the superheater guide construction for certain of the remaining longer superheater platens;

Fig. 12 is a fragmentary sectional plan of the Fig. 11 structure showing the lateral support tube and the superheater platen guide construction for the longer superheater platens;

Fig. 13 is a fragmentary sectional elevation, on an enlarged scale, showing the pin and sleeve guide and support construct-ion associating the innermost tubes of the end superheater platens and the vertical legs of the vapor circuit tubes which act as lateral supports for the superheater platens;

Fig. 14 is a fragmentary sectional plan of the pin and sleeve superheater support tube guide construction indicated in Fig. 13;

Fig. 15 is a fragmentary sectional elevation, on an enlarged scale, showing the pin and clevis superheater tube support construction for the inter-platen cross-over tubes as used at the upper central part of Fig. 8;

Fig. 16 is a fragmentary end elevation of the structure shown in Fig. 15;

Fig. 17 is a fragmentary elevation of the pin and sleeve superheater tube guide construction interlocking the adjacent tube sections at the lower ends of the longer superheater platens;

Fig. 18 is a plan of Fig. 17;

Fig. 19 is a fragmentary elevation, on an enlarged scale of the arrangement of elements at the 90 ends of the lateral support tubes at the end superheater platens;

Fig. 20 is a fragmentary elevation on the line 20*.20 of Fig. 19; and

Fig. 21 is a detail view showing the type of superheater tube guide construction used between adjoining superheater platen tubes in an upper plane just beneath the platen cross-over tubes and at a lower plane just above the level of the horizontal section of the vapor circuit tubes which act as superheater platen spacers.

Fig. 1 of the drawings indicates a steam generating and superheating unit embodying the invention. This unit has a maximum design capacity of 990,000 lbs. of steam per hour at a pressure of the order of 2000 p. s. i. a., and a total steam temperature of 1050 F. The steam is heated to this final temperature in a tubular superheater with pendent tube platens, some of which must be disposed in zones of gas temperatures of the range of 19002200 F. to effect the pertinent total steam temperature. When gases of such temperatures are produced by the burning of coal under slag forming conditions, the pendent superheater tube platens must be spaced sufficiently widely to prevent the bridging of adjacent platens by the accumulation of slag deposits upon the platens. Yet the spacing of the platens must not be so great as to involve excessive installation costs due to increased surface. Also, the platen spacing must not be so great as to decrease efficiency by reason of such heat loss to the furnace walls and heating chamber walls that supenhe'at is reduced. In the illustrative unit there are a plurality of long superheater platens 10 and 12, spaced about 24" apart across a radiation furnace chamber about 22 ft. Wide. The lower ends of these platens are disposed in the highest pertinent gas temperature zone, and above this zone, much shorter superheater platens 14 and 16 are interposed relative to successive long platens.

The longer platens receive steam from a superposed inlet header 18, the steam flow through the successive loops of these platens being indicated by the arrows 20-23 of Fig. 4 of the drawings. Each long platen 12 discharges steam into the intermediate header 30. The tubes of the short platens 14 and 16, with their connections, provide for the continued flow of steam from the intermediate header at positions adjacent the outlets of the long platens, first downwardly as indicated by the arrow 25 and then recurrently, as indicated by arrows 2629, to the outlet header 32. The steam flow indicated by the arrow 27 takes place through cross-overs 34, 38 and 42, so constructed and arranged as to prevent wide variations in heat absorption between the different continuous loop tubes. Thus the upfiow leg 51' of platen 16, receiving a higher degree of heat because of its outside loop position, is connected by cross-over 42 to the less highly heated inside loop downflow leg 55 of the platen 14, and conversely the less highly heated upflow leg 53 of the inner loop of platen 16 is connected by cross-over 34 to the downflow leg 56 of the more highly heated outside loop of platen 14. This cross-over arrangement applies to all of the loop tubes of platens 14 and 16, with an intermediate upflow leg of platen 16 connected by cross-over 38 to the downflow leg 57 of a loop of the platen 14.

Similar cross-over connections connect all of the pairs of front and rear platens, such connections for the front ang 7rear long platens being clearly indicated in Figs. 4 an The superheater platens are pendently supported from the superheater headers 18, 30 and 32 which, in turn, are supported by the structural steel framework of the unit. intermediate the lengths of the loop tubes constituting the superheater platens there are hangers 60 having their upper ends secured to upright plates 62 welded to the header 32. The lower end of each hanger 60 is secured to an upper cross-over 34 by a pin and clevis construction involving the apertured lugs 64 and 66 welded to the cross-over. The lower end of the hanger 60 has an aperture which is aligned with the apertures in the lugs 64 and 66, and a pin is disposed within the three aligned apertures. As shown particularly in Figs. 15 and 16 of the drawings the subjacent cross-overs 68 and 70 are pendently supported in a similar manner from the upper cross-over 34. For example, the cross-over 34 has a downwardly extending lug 72 disposed between the upstanding lugs 74 and 76 welded to the cross-over 68. A pin 78 is disposed within the aligned apertures of lugs 72, 74 and 76 and is welded to the lug 76 as indicated at 80 to prevent accidental displacement of the pin from its operative position. Similar pin and clevis supports are disposed between the cross-overs 68 and 70, and such arrangements continue to the lowest cross-over 42, as indicated in Fig. 8.

Because the outlet ends 82 of the tubes of the short superheater platens 14 are bent laterally toward the superheater outlet header 32, as indicated in Figs. 6 and 8, the upright end portions of these tubes have fixed thereto opposite lugs which are clamped between bars 84 and 86, and these bars are secured to upright hangers 88, the upper ends of which are suitably attached to superposed steel work.

To maintain the desired spacing of the superheater platens the latter are connected to the transversely and horizontally disposed sections and 92 of superheater lateral support tubes which are shown particularly in Figs. 5 and 6. These tubes conduct steam from the inlet header 18 to the intermediate header 30. One of the tubes has an. inlet or inlet portion 94 leading from -the right handsend of the inlet header, as shown in Fig. 5. :It continues through a dowrfiow leg 93 leading down- .wardly at the right hand side of the superheater platens toa positionin transverse alignment with the space be- .tween the innermost legs of theplatens and 14 to the level of its transverse section 90, the down flow leg being held in operative position by guide spacer constructions (see Figs. 13 and 14), including the sleeves or apertured lugs97102 and the associated pins 104-and 106, so arranged as to permit relative longitudinal movements of the tubular sections 93 and 55. The sleeves 98 Band 101 are welded to the tubular section or downflow leg95 of the superheater platen lateral suppoit tube,-and

the remaining sleeves are welded to the platen tube section 55 with each of the pins 104 and 106 welded to a sleeve at one position to prevent the pin from dropping out ,of operative position. Such a guide spacer construction is disposed at least four positions at each side of the high temperature superheater formed by all of the-platens 10, 12, 14 and 16. Such positions are indicated at A,-B, C, D,'E and F in Figs. 5 and 6.

The steam flow in the pertinent superheater lateral support tube or circuit tube continues from the downflow leg through the horizontal section 90 to the upflow leg 110 at the left hand side of Fig. 5 and thence upwardly through that leg to the position 112 (Fig. 6) whence 'the'flow proceeds through the inclined leg 114 to opposite end, or left hand end (Fig. 5) of the intermediate head- The lateral support tube or circuit tube just described provides, through inter-tube connections to be described below, for the maintenance of the spacing of the front platens 10 while a second, but reversely arranged support tube or circuit tube is similarly effective upon therear 'platens 12. This second circuit tube has a tubular inlet or inlet section 120 leading from the left hand end of the inlet header 18 as it is shown in Fig. 5. At the position 122 the second circuit flow continues through an inclined leg 124- (Fig. 6) extending to a vertical plane intermediate the innermost loop tubes of all of the rear platens 12 and 16. From this position the flow continues through a vertical downfiow leg 126 to the level of the transverse section 92, extending through the rear -platens. The downfiow leg 1216 is held to one of the innermost loop tubes of a rear platen by a guide and spacer construction similar to that shown in Figs. 13 and 14. From the'outlet end of section 92 (right hand side of the superheater as shown in Fig. 5) the flow continues through an upfiow leg 12S extending directly upwardly to the outlet section 139 which is connected to the opposite or right hand end of header 311, as it is shown in Fig. 5.

-Fig. 12 is a fragmentary plan showing the guide and/ or guide spacer construction by which the horizontal sec- :These lugs are short bars extending longitudinally of the tube as indicated in Fig. 11. The radially outward ends of these lugs are spaced slightly (about /s) from the ends, of limit lugs 144 and 146 welded to the tube 90. A similar arrangement of oblique lugs 152 and 154 is provided on the opposite. side of tube 90 to complete the means for limiting the lateral movement of both long and short platens.

To further maintain operative relationship of the guide tube. section (or lateral support tube horizontal section) aud the platen of tubes 55 and 95, support lugs-158 andv160arewelded to the tubes 55 and 95 of some .of

' One function of the support lugs is to prevent the hori- 2il2,. of the cyclone 204i. air is admitted tangentially through inlet 2%, and the outlet 208 in a turbulent condition.

. accumulations.

'zontal sectioni of the lateral support tube from bending or bowing out of operative position.

The support lug arrangement is indicated in Fig. 5.

vHere, every fourth or fifth platen such as 51 has the lower support lugs 158 and at positions H and K but omits the upper lugs of Fig. 9. At intermediate positions P, Q, R and S, every fourth platen 51A omits the lower support lugs but does have the upper lugs-156 and 162, as indicated in the Fig. 9 arrangement. In this Fig. Sembodiment there are no support lugs secured to the short platens.

Figs. 19 and 20 show the arrangement of guide or spacer structures at the 90 bends at the ends of the lateral support tube 90. Here, diametrically opposite stop lugs 164 and 166' are welded to tube 90 in position to contact the platen tubes 55 and 95. This arrangement is reversed atthe opposite end of tube 90 so that the counterparts of lugs 164 and 166' are disposed at the right hand side of (relative to Figs. 5 and 19) the platen tubes corresponding to tubes 36 and 5'5.

, The successive tube portions at the lower parts of the -long platens 1'8 and 12 are spaced more closely than the platen tube portions in zones above the level of the lower ends of the short platens. (Figs. 4 and 7) the successive platen tube portions are spaced as indicated in Figs. 17 and 18. Here, representative tube portions, such as 17%; and 172, are held in closely their spaced positions by such guides or guide structures as that shown in Fig. 21, these guides permitting relative longitudinal movements of the successive tubes. In Fig. 21 the tube 55 has the T lug 18b welded thereto, with the stem of the T capable of sliding movement relative to the converging and co-acting lugs 182 and 184, welded to the tube 55. The lug 182 has the inwardly bent end portion 136 disposed under one part of the head of ,T 180, and the lug 184 has an oppositely arranged angled end 188.

The above described superheater is disposed in a high temperature (22004800 F.) zone in the upper part of a secondary furnace chamber 260, receiving combustion products from a coal burning cyclone furnace constructed and arranged in a manner similar to that indicated in the U. S. patent to Bailey et al. 2,357,301 of September 5, 1944. In the operation of this furnace, crushed coal andprirnary air are deliveredtangentially to the inlet High temperature secondary combustion products exit from the cyclone through its Although most of the incombustible residue is separated from the combustion-gases as slag, in the primary furnace chamber 210 (to exit therefrom through slag discharge opening 212) the gases exiting from chamber 210 and passing the tubularscreens 212216 and then into the secondary furnace chamber 20% still, carry appreciable amounts ofslag particles which are in a sticky condition, due to the pertinent high temperatures. Such particles stick to and accumulate upon the lower-parts of the long superheater platens 10 and 12, and this condition emphasizes the importance of maintaining the wide spacing (he. 24") of the long platensttoprevent the bridging of these platens by slag Such bridging would decrease the heat transfer rates to'the tubes of the above described superheater, and would further decrease the effectiveness of -the pertinent unit by increasing draft loss and by prevent- In the zones T and W 7 ing the unit from attaining the pertinent high superheat (i. e., 1000 F. to 1100 F.).

The above described superheater may be described as a radiant superheater. It is also a high temperature secondary superheater receiving superheated steam through the conduit 218 from the outlet header 220 of a primary superheater disposed in the downflow gas pass 222 and including a plurality of banks of tubes similar to 224. Some of these banks of tubes receive steam from the header 226 and are disposed in an adjoining parallel division of gas pass 222. The inlet header 221 for the bank of tubes 224 receives steam from the drum 248 through the conduit 223 and the tubes 225 and 227.

Between the primary superheater bank of tubes 224, and the secondary superheater, and in the upper part of the gas pass is a steam reheater 228 including the banks of tubes 229-231 leading from the reheater inlet header 232 to the reheater outlet header 234.

Beyond the outlet 236 of the downflow gas pass 222 the heating gases pass through the flue 238 to an economizer and then to an airheater (not shown).

The gas outlet of the gas pass is separated from the furnace by an inclined wall 240' defined by steam generating tubes leading from the water drum 242, through and/or past the screens 212-2316, through the gas pass and furnace chamber dividing wall 244, and through the gas pass screen 246 to the steam and water drum 248.

The inclined gas pass wall 240 includes upward extensions of the wall tube sections 250 at the rear of the unit, and also, upward extensions of the tube sections of the screens 2'13216, the lowermost parts of the steam generating tubes leading along the wall 250 and through the screens 213216 are arranged as shown in Fig. 1 to form, in conjunction with high temperature refractory wall material, the refractory wall and floor surfaces at the bottom of the primary and secondary furnace chambers. Similar refractory material is associated with other steam generating tubes to present the walls and other boundaries 256259 of the cyclone furnace. Upward extensions of the tube sections forming the screen 212 form the walls 260 and 261 separating the primary furnace chamber 210 from the lower furnace chamber 200, and further upward extensions lead along the furnace wall 264 and the roof 266 to the drum 248.

Also extending along the wall 264 and the roof 266 are extensions of the riser tubes 270 leading from the upper cyclone header 272. This header is connected to the lower cyclone header 274 by the wall tubes 276 of the cyclone. Circulators 278 connect the header 274 and the drum 242.

The side walls of the pertinent unit include steam generating tubes appropriately connected to the drums 242 and 248 by headers such as 280 and 282, and suitable circulator tubes. Appropriate downcomer tubes 300 lead downwardly from the water space of the drum 248 to the lower drum 242 and to the lower side wall headers. The downcomers are secured together in the rectangular arrangement indicated at 302, for enhancing their arrangement as to its structural strength.

While in accordance with the provisions of the statutes we have illustrated and described herein the best form of our invention now known to us, those skilled in the art will understand that the changes may be made in the form of the apparatus disclosed without departing from the spirit of the invention covered by our claims, and that certain features of our invention may sometimes be used to advantage without a corresponding use of other features.

What is claimed is:

1. In a vapor generating superheating unit a high temperature furnace chamber; means for the delivery of high temperature combustion products to said chamber; vapor generating means including wall tubes along the walls of said chamber; a superheater including pendent superpart of the secondary 8 heater units disposed within the upper part of said chamber, each of said units consisting of front and rear superheater tube platens with the front platens of the various units disposed in one row across the chamber and the rear platens of the units disposed in a rear row across the chamber; a superheater inlet header; another superheater header disposed adjacent the upper part of the superheater; a first superheater lateral support tube having a downflow leg flowing fluid from one end of the inlet header down one side of the superheater to a level intermediate the upper and lower extremities of the superheater, said lateral support tube continuing flow of fluid from the lower part of said downflow leg transversely of the front row of superheater platens and then upwardly through an upflow leg to the upper part of the superheater and thence through an inclined section to the other header; a second superheater lateral support tube flowing fluid from the other end of the inlet header through an upper section to a downwardly inclined section and then to a position aligned with the rear row of the superheater platens, then through a downflow leg at the opposite side of said superheater to a position intermediate the upper and lower extremities of the superheater and then through a horizontally disposed transverse portion extending through the rear superheater platens to said one side of the superheater, said second superheater lateral support tube then continuing fluid flow through an upfiow leg to the other superheater header; and metallic members secured to the horizontal sections of the superheater lateral support tubes between successive platens to maintain the platen spacing.

2. In a vapor generating superheating unit a high temperature furnace chamber; means for the delivery of high temperature combustion products to said chamber; vapor generating means including wall tubes along the walls of said chamber; a superheater including pendent superheater units disposed within the upper part of said chamber; each of said units consisting of. front and rear superheater tube platens with the front platens of the various units disposed in one row across the chamber and the rear platens of the units disposed in a rear row across the chamber; a superheater inlet header; another superheater header disposed adjacent the upper part of the superheater; a first superheater lateral support tube having a downflow leg flowing fluid from one end of the inlet header down one side of the superheater to a level intermediate the upper and lower extremities of the super- .heater; said lateral support tube continuing flow of fluid from the lower part of said downflow leg transversely of and centrally through the superheater platens of the front row, then upwardly through an upflow leg to the upper part of the superheater and thence through an inclined section to the other header; a second superheater lateral support tube flowing fluid from the other end of the inlet header through an upper section to an inclined section and then to a position aligned with the rear row of the superheater platens, thence through a downflow leg at the opposite side of said superheater to a position intermediate the upper and lower extremities of the superheater and then through a horizontally disposed transverse portion extending through the rear superheater platens to said one side of the superheater; said second superheater lateral support tube then continuing fluid flow through an upflow leg to the other superheater header; and metallic members secured to the horizontal sections of the superheater lateral support tubes between successive platens to maintain the platen spacing; means affording pendent support for the inclined sections, and means tying the upflow and downflow legs of the lateral support tubes to the adjacent platens.

3. In a vapor generating superhcating unit a high temperature furnace chamber; means for the delivery of high temperature combustion products to said chamber; vapor generating means including wall tubes along the walls of said chamber; a superheater including pendent superheader down one side of the superheater to a level intermediate the upper and lower extremities of the superheater; said lateral support tube continuing flow of fluid from the lower part of said downflow leg transversely through the superheater platens of the front row and then upwardly through an upflow leg to the upper part of the super-heater and thence through an upwardly inclined section to the other header; a second superheater lateral support tube having a downflow leg flowing fluid from the first header through a downwardly inclined section to a position aligned with the rear row of the superheater platens and thence through the downflow leg at the opposite side of said superheater to a position intermediate the upper and lower extremities of the superheaterand then through a horizontally disposed transverse portion extending through the rear superheater platens to said one side of the superheater; said second superheater lateral support tube then continuing flow through an upflow leg to the other superheater header; metallic members secured to the horizontal sections of the superheater lateral support tubes between successive platens to maintain the platen spacing; and means secured to some ot the superheater platens to guide and support the, superheater lateral support tubes.

4. In a fluid heater having a vertically extending heating gas pass, a pair of headers, a vertically arranged bank of vapor heating tubes in said heating gas pass andcornprising a plurality of horizontally spaced tube platens arof said headers and tubes to permit relative vertical movement of said platens and spacer tube, and platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and adjacent said platen tube legs to maintain said platens in their spaced relation, while permitting vertical movement of said platens.

5. In a fluid heater having a vertically extending heating gas pass, a pair of horizontally arranged headers, a vertically arranged bank of vapor heating tubes in said heating gas pass and comprising a plurality of horizontally spaced tube platens arranged in parallel vertical planes, each of said tube platens comprising at least one return bend vapor heating tube having vertically arranged horizontally spaced tube legs, said return bend tube being connected at its opposite ends to said headers, 21 fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens substantially normal to the planes thereof at a position intermediate the upper and lower ends of said platens, means for pendently supporting the weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, and platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and adjacent said platen tube legs to maintain said platens in their spaced relation, while permitting vertical movement of said platens.

6. In a fluid heater having a vertically extending heating gas pass, a pair of headers, a vertically arrangedbank of vapor heating tubes in said heating gas pass andcomhorizontally spaced tube legs and connected at its opposite ends to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens at a position intermediate the upper and lower ends of said platens, means for pendently supporting the weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, and platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and adjacent at least some of the tube legs of said platens to maintain said platens in their spaced relation, ,while permitting vertical movement of said platens.

7. In a fluid heater having a vertically extending heating gas pass, a pair of horizontally arranged headers,-a vertically arranged bank of vapor heating tubes in said heating gas pass and comprising a plurality of horizontally spaced tube platens arranged in parallel vertical planes, each of said tube platens comprising a plularity of nested return bend vapor heating tubes, each return bend tube having vertically arranged horizontally spaced tube legs and connected at its opposite ends ,to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens substantially normal to the plane thereof at a position intermediate the upper and lower ends of said platens, means for pendently supporting the weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, and platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and adjacent at least some of the tube legs of said platens to maintain said platens in their spaced relation, while permitting vertical movement of said platens.

8. Ina fluid heater having a vertically extending heating gas pass, a pair of headers, a vertically arranged bank of vapor heating tubes in said heating gas pass and comprising a plurality of horizontally spaced tube platens arranged in vertical planes, each of said tube platens comprising a plurality of nested return bend vapor heating tubes, each return bend tube having vertically arranged horizontally spaced tube legs and connected at its opposite ends to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens at a position intermediate the upper and lower ends of said platens, means for pendently supporting the weight of said headers, and tubes to permit relative vertical movement of said platens and spacer tube, and platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and close to adjacent tube legs of said platens, and metallic members secured to opposite sides of said adjacent tube legs'and cooperating with the metallic members on said horizontal tube leg portion to maintain said platens in their spaced relation, While permitting vertical movement of said platens.

9. In a fluid heater having a vertically extending heating gas pass, a pair of headers, a vertically arranged bank of vapor heating tubes in said heating gass pass and comprising a plurality of horizontally spaced tube platens arranged in vertical planes, each of said tube platens com prising at least one return bend vapor heating tube having vertically arranged horizontally spaced tube legs, said return bend tube being connected at its opposite ends to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens, means for pendently supporting the weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of said platen tube legs to maintain said platens in their spaced relation, while permitting vertical movement of said platens, and means arranged to permit limited vertical movement of said horizontal tube leg portion relative to said platens.

10. In a fluid heater having a vertically extending heating gas pass, a pair of horizontally arranged headers, a vertically arranged bank of vapor heating tubes in said heating gas pass and comprising a plurality of horizontally spaced tube platens arranged in parallel vertical planes, each of said tube platens comprising a plurality of nested return bend vapor heating tubes, each return bend tube having vertically arranged horizontally spaced tube legs and connected at its opposite ends to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens substantially normal to the planes thereof at a position intermediate the upper and lower ends of said platens, means for pendently supporting the weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of and adjacent at least some of the tube legs of said platens to maintain said platens in their spaced relation, While permitting vertical movement of said platens, and means arranged to permit limited vertical movement of said horizontal tube leg portion relative to said platens.

11. In a fluid heater having a vertically extending heating gas pass, a pair of horizontally arranged headers, a vertically arranged bank of vapor heating tubes in said heating gas pass and comprising a plurality of horizontally spaced tube platens arranged in parallel vertical planes, each of said tube platens comprising a plurality of nested return bend vapor heating tubes, each return bend tube having vertically arranged horizontally spaced tube legs and connected at its opposite ends to said headers, a fluid cooled platen spacer tube connected at its opposite ends to said headers and having a substantially horizontal tube leg portion extending through said platens substantially normal to the planes thereof at a position intermediate the upper and lower ends of said platens, means for pendently supporting the Weight of said headers and tubes to permit relative vertical movement of said platens and spacer tube, platen spacer means including metallic members secured at spaced positions along the length of said horizontal tube leg portion and disposed on opposite sides of adjacent tube legs of said platens, and metallic members secured to opposite sides of said adjacent tube legs and cooperating with metallic members on said horizontal tube leg portion to maintain said platens in their spaced relation, while permitting vertical movement of said platens, and means arranged to permit limited vertical movement of said horizontal tube leg portion relative to said platens, said last named means including metallic members secured to at least some of said tube legs at positions immediately above and below said horizontal tube leg portion.

References Cited in the file of this patent UNITED STATES PATENTS 1,924,918 Fischer Aug. 29, 1933 2,015,328 Wood Sept. 24, 1935 2,033,077 Kerr et a1. Mar. 3, 1936 2,114,224 Jacobus Apr. 12, 1938 2,244,144 Drewry June 3, 1941 2,308,762 Krug Jan. 19, 1943 2,310,801 Mayo et al Feb. 9, 1943 2,477,950 Bailey Aug. 2, 1949 2,519,566 Hamm Aug. 22, 1950 2,536,072 McDonald Jan. 2, 1951 FOREIGN PATENTS 832,563 France Aug. 29, 1938 872,266 France June 3, 1942 

